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The Challenge: Make a Thermometer

How can we measure temperature?

The earliest devices used to measure temperature were called thermoscopes. They consisted of a big glass bulb with a long tube extending downwards into a container of colored water or wine. Some of the air in the bulb was expelled before placing it in the liquid, causing the liquid to partially rise into the tube. As the remaining air in the bulb was heated or cooled, the level of the liquid in the tube would vary, reflecting the change in the air temperature. An engraved scale on the tube provided a way of measuring the fluctuations.